While the highly advanced technologies bring a lot of conveniences to human, they also cause many serious damages to people's living environment. Therefore, it has become a focus among all countries in the world to develop a reasonable way of waste disposal. To comply with the increasingly strict demands for environment protection, different waste decomposition processes are developed. Among others, the so-called fluidized bed reactor has drawn the world's attention.
Please refer to FIG. 1 that is a block diagram of a conventional fluidized bed reactor. As shown, the fluidized bed reactor includes a reactor 10, into which charges 11 are fed. To enhance the mass-energy transfer function of the reactor 10, a carrier gas 12 is applied in the operation of the reactor 10. The carrier gas 12 serves to assist in heat supply, mass transfer, etc., and is sometimes used as part of the reactant in the reaction. The product from the reaction in the reactor 10 is then sent to and condensed and deposited in a condensation tank 20 to generate an oil-water mixture 21 and a mixed gas 22 containing the carrier gas 12.
The conventional fluidized bed reactor shown in FIG. 1 has the following drawbacks in the implementing process thereof:                The carrier gas is typically nitrogen to maintain the reaction system in an anaerobic state. Since the nitrogen would adversely increase the operation cost, it is uneconomical to expand the reaction system; and        The carrier gas must be applied from outside of the system, which would dilute the gas generated from the reaction and lessen the purity and utility value of the reaction-generated gas.        
It is therefore an important issue to improve the above described conventional fluidized bed reactor.
FIG. 2 is a block diagram showing the implementing process of another conventional fluidized bed reactor, which is developed for use in waste pyrolytic reaction. In this type of fluidized bed reactor, combustible gas generated in the pyrolysis is recycled and used as the fluidizing gas. Therefore, it is not necessary to apply a carrier gas from outside into the reactor 10. The mixture and gas generated in the reactor 10 are condensed and deposited in the condensation tank 20, and the purified reaction-generated gas 23 is recycled and directly guided into the reactor 10 to substitute for the carrier gas.
U.S. Pat. No. 5,728,271 granted to Resource Transformations International Ltd. as well as the research on Hamburg Pyrolysis Plant conducted by Kaminsky et al. in the Hamburg University, Germany are relevant to the waste disposal using the fluidized bed reactor. However, in these two cases, there is only a simple description about the recycling of combustible gas for use as fluidizing gas without details about an operable system therefor. As a matter of fact, to recycle the reaction-generated gas in the fluidized bed, many other factors, such as the maintaining of stable pressure in the system, the expelling of ultra reaction-generated gas, the control of transferred gas, the preheating of gas, etc., must be taken into consideration at the same time.